3D-HEVC depth video information hiding method based on single-depth intra mode

ABSTRACT

The present invention disclosed a 3D-HEVC depth video information hiding method based on single-depth intra mode, which comprises information embedment part and information extraction part. During information embedment, if the pixels in the candidate list are equal using the encrypt information to modulate the index of the pixel and completes the embedment. If the pixels are different, judging the neighboring CU of the CU whose depth is 2 or 3 and modulating the index of the pixel to complete embedment of the hidden information. The advantage of the present invention is high security, low calculation complexity and small influence on data rate.

CROSS REFERENCE OF RELATED APPLICATION

The application claims priority under 35 U.S.C. 119(a-d) to CN201610534911.1, filed Jul. 5, 2016.

BACKGROUND OF THE PRESENT INVENTION

Field of Invention

The present invention relates to a video information hiding technology,particularly involves a 3D-HEVC depth video information hiding methodbased on single-depth intra mode.

Description of Related Arts

With the development of the network and communication technology,information security is more and more important and pressing.Information hiding technology is an effective way to deal with thisproblem. 3D video became more and more popular in movie industry and forentertainment application so the 3D extension of HEVC (High EfficiencyVideo Coding) standard namely 3D-HEVC standard attracts much attention.Depth video is an important part of 3D video which is used for drawingcolor virtual viewpoint and not for direct view. Partial depthdistortion of depth video will not cause the distortion of color virtualviewpoint, which makes the depth video information hiding technologyunder 3D-HEVC standard has significant meaning.

Conventionally, the video information hiding algorithm mainly based onsingle-viewpoint video coding standard. The information hidingtechnology based on single-viewpoint HEVC standard achieved preliminarydevelopment with the wide application of HEVC standard. For example, theHEVC intra prediction mode related information hiding algorithm broughtup by WANG et al. which needs re-encoding using the modified predictionmode and thus has high complexity; Tew et al. proposed an algorithm inwhich the unit splitting depends on the embedded information and theparity modulation of quantized non-zero DCT coefficient is taken intoconsideration, as a result, the whole performance of the algorism getsimproved. However, the 3D video information hiding algorithms are few. Ablind watermarking algorithm of 3D video based on quantization indexmodulation brought up by Yang embeds the watermarking information in theDCT coefficients of the depth video. Since the algorithm embedswatermarking information in the image domain of the depth video, theembedded information may be lost after compressing. The conventional 3Dvideo information hiding algorithm for compression domain is based onand extends from single-viewpoint H.264 standard, such as a reversiblemulti-view video information hiding algorithm brought up by SONG whichhides the information in motion vectors of coding block in b4 frameusing inner product. The method achieves good imperceptibility and isreversible. The 3D-HEVC has a significant better compression performancethan H.264, which is capable of encoding a higher definition videosequence. So it is necessary to carry out research on 3D videoinformation hiding algorithm based on 3D-HEVC coding standard. Sincethere are many smooth regions and edge regions in depth video, theperformance of the information hiding algorithm is not able to achievepredicted effects if simply applies the information hiding technology ofthe color video on the depth video. In 3D-HEVC, there is a “single-depthintra mode” which is designed for the smooth region of the depth videowhile 3D video coding standard extended from single-viewpoint H.264 isnot equipped, this provides a new way to embed the hidden information indepth video.

SUMMARY OF THE PRESENT INVENTION

An object of the present invention is to provide a 3D-HEVC depth videoinformation hiding method based on single-depth intra mode, which hashigh security level, low complexity and small effect on bitrate.

In order to solve the conventional technical problem the presentinvention provides a 3D-HEVC depth video information hiding method basedon single-depth intra mode, comprising information embedment andinformation extraction;

Therefore steps for the information embedment are as follow:

(1)_1, representing an original 3D (three dimensional) video by S_(org),denoting a left view color video of S_(org) as L_(org) ^(c), denoting aleft view depth video corresponding to L_(org) ^(c) as L_(org) ^(d),denoting a right view color video of S_(org) as R_(org) ^(c), denoting aright view depth video corresponding to R_(org) ^(c) as R_(org) ^(d);wherein L_(org) ^(c), L_(org) ^(d) and R_(org) ^(c), R_(org) ^(d) arecompressed and encoded through a 3D-HEVC standard coding platform togenerate a target video stream str.bin_(org); M and N denote widths andheights of frames in L_(org) ^(c), L_(org) ^(d), R_(org) ^(c) andR_(org) ^(d) respectively; F denotes the number of frames contained inthe L_(org) ^(c), L_(org) ^(d), R_(org) ^(c) or R_(org) ^(d); Wrepresents hidden information to be embedded, wherein W comprises ann-bit value, W={w₁, w₂, . . . , w_(i), . . . , , w_(n-1), w_(n)}, w₁,w₂, w_(i), w_(n-1) and w_(n) represent a first bit value, a second bitvalue, an i-th bit value, an n−1-th bit value and an n-th bit value in Wrespectively; values of w₁, w₂, . . . , w_(i), w_(n-1) and w_(n) are 0or 1, 1≦i≦n,

${n \in \left\lbrack {1,\frac{M \times N \times F}{8 \times 8}} \right\rbrack};$

(1)_2, using logistics chaos mapping generates a pseudo-random binarysequence that contains n bits value as a key E, E={e₁, e₂, . . . ,e_(i), . . . , e_(n-1), e_(n)}; processing every bit value of E and thecorresponding bit value of W with XOR to generate encrypted informationW′, W′={w′₁, w′₂, . . . , w′_(i), . . . , w′_(n-1), w′_(n)}; wherein theinitial information of the key E is given arbitrarily; e₁, e₂, e_(i),e_(n-1) and e_(n) represent a first bit value, a second bit value, ani-th bit value, an n−1-th bit value and an n-th bit value in Erespectively; the values of e₁, e₂, e_(i), e_(n-1) and e_(n) are 0 or 1;w′₁, w′₂, w′_(i), w′_(n-1), and w′_(n) represent a first bit value, asecond bit value, an i-th bit value, an n−1-th bit value and an n-th bitvalue in W′ respectively; the values of w′₁, w′₂, w′_(i), w′_(n-1) andw′_(n) are 0 or 1, 1≦i≦n;

(1)_3, parsing each frame of the target video stream str.bin_(org) andsetting a current frame needing to be parsed in the target video streamstr.bin_(org) as a current frame;

(1)_4, determining whether the current frame is a left view depth frameor a right view depth frame, if yes executing step (1)_5 or else step(1)_8;

(1)_5, parsing each CTU (coding tree unit) of the current frame andsetting a current CTU needing to be parsed in the current frame as acurrent parse block, then executing step (1)_6;

(1)_6 according to an optimal splitting mode of the current parse block,paring every coding mode corresponding to CU (coding unit) in thecurrent parse block after being split; representing a k th CU in thecurrent parse block by B_(org) ^(k); wherein a corresponding coding modeof B_(org) ^(k), is marked as M_(org) ^(k), k is a positive integer,kε[1,64]; a size of the B_(org) ^(k) is 8×8, 16×16, 32×32 or 64×64,M_(org) ^(k)ε{intra coding mode, single-depth intra coding mode};executing the following steps of:

(1)_6a, setting a CU under processing in the current parse block as acurrent CU;

(1)_6b, assuming the current CU is B_(org) ^(k), wherein if the codingmodel M_(org) ^(k) corresponding to the current CU is an intra codingmode then executing step (1)_6i; if the coding model M_(org) ^(k)corresponding to the current CU is a single-depth intra coding mode thenexecuting step (1)_6c;

(1)_6c, according to a coding theory of a single-depth intra codingmode, constructing a pixel candidate list of the coding mode M_(org)^(k) corresponding to the current CU, which is marked as list_(org)^(k); wherein list_(org) ^(k) contains 2 pixels; a first pixel is markedas y_(org) ^(k,1), an index of which is 0; and a second pixel is markedas y_(org) ^(k,2) an index of which is 1, 0≦y_(org) ^(k,1)≦255,0≦y_(org) ^(k,2)≦255; reading a value e_(j) of a j th bit in the key Eand a value w′_(i) of an i th bit from the encrypted information W′;wherein 1≦j≦n, an initial value of j is 1, 1≦i≦n, a initial value of iis 1; executing step (1)_6d;

(1)_6d, determining whether y_(org) ^(k,1) equals to y_(org) ^(k,2), ifyes, executing step (1)_6e, else, executing step (1)_6f;

(1)_6e, if e_(j) is 1, using w′_(i) to modulate an index of a pixelselected by the coding mode M_(org) ^(k) corresponding to the current CUwhen encoding the current CU and obtaining an index of the pixel afterbeing embedded with hidden information when the current CU goes throughencoding; entropy-coding the index of the pixel selected by the codingmode M_(org) ^(k) corresponding to the current CU after being embeddedwith the hidden information when the current CU goes through encoding;completing embedment of the hidden information in the current CU; thenj=j+1 and i=i+1, executing step (1)_6i; otherwise, if e_(j) is 0, thenj=j+1, executing step (1)_6i; where “=” is an assignment operator inj=j+1 and i=i+1;

(1)_6f, parsing a depth of the current CU, if the depth is 2 or 3 thenexecuting step (1)_6g; if the depth is 0 or 1, then executing step(1)_6i, depthε{0, 1, 2, 3};

(1)_6g, determining whether a coding mode of a right neighboring CU or abelow neighboring CU is the single-depth intra coding mode, if yes,executing step (1)_6i, else, executing step (1)_6h; wherein the rightneighboring CU is a neighboring CU which is on a right side of thecurrent CU; the below neighboring CU is a neighboring CU which is belowthe current CU;

(1)_6h; determining whether a prediction mode of a right aboveneighboring CU, the right neighboring CU, a right below neighboring CU,a left below neighboring CU and the below neighboring CU of the currentCU belongs to a corresponding mode range respectively; if not, usingw′_(i) to modulate the index of the pixel selected by the coding modeM_(org) ^(k), corresponding to the current CU when encoding the currentCU and obtaining the index of the pixel after being embedded with thehidden information when the current CU goes through encoding;entropy-coding the index of the pixel selected by the coding modeM_(org) ^(k), corresponding to the current CU after being embedded withthe hidden information when the current CU goes through encoding;

completing the embedment of the hidden information in the current CU;i=i+1, executing step (1)_6i; else, executing step (1)_6i; wherein theright above neighboring CU is a neighboring CU which is above and on theright side of the current CU; the right below neighboring CU is aneighboring CU which is below and on the right side of the current CU;the left below neighboring CU is a neighboring CU which is below and ona left side of the current CU;

(1)_6i, setting a next CU needing to be processed of the current parseblock as the current CU and executing step (1)_6b; moving on until aprocess of all the CU in the current parse block is completed and thenexecuting step (1)_7;

(1)_7, setting a next CTU needing to be parsed of the current frame as acurrent parse block and executing step (1)_6; moving on until a processof all the CTU in a current frame is completed and then executing step(1)_8;

(1)_8, setting a next frame needing to be parsed in the target videostream str.bin_(org) as a current frame and executing step (1)_4; movingon until a process of all the frames in the target video streamstr.bin_(org) is completed and obtaining a video stream str.bin_(dec)which embedded with the hidden information;

(1)_9, transmitting information of an initial value which generates thekey E to an information extraction terminal;

An information extraction method comprising following steps of:

(2)_1, setting the video stream which embedded with the hiddeninformation as the target video stream str.bin_(dec);

(2)_2, according to the information of the initial value which generatesthe key E transmitted from an information embedment terminal, generatinga same key E using logistics chaos mapping;

(2)_3, parsing each frame of the target video stream str.bin_(dec) andsetting a current frame needing to be parsed in the target video streamstr.bin_(dec) as a current frame;

(2)_4, determining whether the current frame is the left view depthimage or the right view depth image; if yes, executing step (2)_5, else,executing step (2)_8;

(2)_5, parsing the current frame by the CTU and setting the current CTUneeding to be parsed in the current frame as a current parse block; thenexecuting step (2)_6;

(2)_6, according to an optimal splitting mode of the current parseblock, parsing every coding mode corresponding to the CU in the currentparse block after being split; representing a k th CU in the currentparse block by B_(dec) ^(k); wherein a corresponding coding mode ofB_(dec) ^(k) is marked as M_(dec) ^(k), k is a positive integer,kε[1,64]; a size of the B_(dec) ^(k) is 8×8, 16×16, 32×32 or 64×64,M_(dec) ^(k)ε{intra coding mode, single-depth intra coding mode}; thenexecuting following steps of:

(2)_6a, setting a CU under processing of the current parse block as acurrent CU;

(2)_6b, assuming the current CU is B_(dec) ^(k); wherein if the codingmodel M_(dec) ^(k) corresponding to the current CU is the intra codingmode then go to step (2)_6i; if the coding model M_(dec) ^(k)corresponding to the current CU is the single-depth intra coding modethen go to step (2)_6c;

(2)_6c, according to the coding theory of the single-depth intra codingmode constructing a pixel candidate list which is marked as list_(dec)^(k) of the coding mode M_(dec) ^(k) corresponding to the current CU;wherein list_(dec) ^(k) contains 2 pixels; a first pixel is marked asy_(dec) ^(k,1) and a second pixel is marked as y_(dec) ^(k,2), 0≦y_(dec)^(k,1)≦255, 0≦y_(dec) ^(k,2)≦255; reading a value of a j th bit e_(j) inthe key E, 1≦j≦n, wherein an initial value of j is 1; executing step(2)_6d;

(2)_6d, determining whether y_(dec) ^(k,1) is equal to y_(dec) ^(k,2),if yes, executing step (2)_6e, else, executing step (2)_6f;

(2)_6e, if e_(j) is 1, parsing an index of a pixel selected by thecoding mode M_(dec) ^(k) corresponding to the current CU after beingembedded with hidden information and obtaining an i th bit value of theencrypted information ŵ′_(i); completing an extraction of the hiddeninformation in the current CU; j=j+1 and i=i+1, executing step (2)_6i;otherwise, if e_(j) is 0, then j=j+1, executing step (2)_6i; wherein1≦i≦n, an initial value of i is 1, ŵ′_(i) is 0 or 1, “=” is a assignmentoperator in j=j+1 and i=i+1;

(2)_6f, parsing a depth of the current CU, if the depth is 2 or 3 thenexecuting step (2)_6g; if the depth is 0 or 1, then executing step(2)_6i, depthε{0, 1, 2, 3};

(2)_6g, determining whether a coding mode of a right neighboring CU or abelow neighboring CU is the single-depth intra coding mode, if yes,executing step (2)_6i, else, executing step (2)_6; wherein the rightneighboring CU is a neighboring CU which is on the right side of thecurrent CU; the below neighboring CU is a neighboring CU which is belowthe current CU;

(2)_6h, determining whether a prediction mode of a right aboveneighboring CU, the right neighboring CU, a right below neighboring CU,a left below neighboring CU and the below neighboring CU of the currentCU belongs to a corresponding mode range respectively; if not, parsingan index of a pixel selected by the coding mode M_(dec) ^(k)corresponding to the current CU after being embedded with the hiddeninformation and obtaining an i th bit value of the encrypted informationŵ′_(i); completing an extraction of the hidden information in thecurrent CU; i=i+1, executing step (2)_6i; else, executing step (2)_6i;wherein the right above neighboring CU is a neighboring CU which isabove and on the right side of the current CU; the right belowneighboring CU is a neighboring CU which is below and on the right sideof the current CU; the left below neighboring CU is a neighboring CUwhich is below and on the left side of the current CU;

(2)_6i, setting a next CU needing to be processed in the current parseblock as a current CU and executing step (2)_6b; moving on until aprocess of all the CU in the current parse block is completed and thenexecuting step (2)_7;

(2)_7, setting a next CTU needing to be parsed of the current frame as acurrent parse block and executing step (2)_6; moving on until a processof all the CTU in the current frame is completed and then executing step(2)_8;

(2)_8, setting a next frame needing to be parsed in the target videostream str.bin_(dec) as the current frame and executing step (2)_4;moving on until a process of all the frames in the target video streamstr.bin_(dec) is completed and completing the extraction of the hiddeninformation;

(2)_9, obtaining n bit values of encrypted information and constructingan encrypted information Ŵ′, Ŵ′={ŵ′₁, ŵ′₂, . . . , ŵ′_(i), . . . ,ŵ′_(n-1), ŵ′_(n)} processing every bit value of the encryptedinformation of Ŵ′ and the corresponding bit value of the key E with XORand generating the decrypted information Ŵ, Ŵ′={ŵ₁, ŵ₂, . . . , ŵ_(i), .. . , ŵ_(n-1), ŵ_(n)}; wherein ŵ′₁, ŵ′₂, ŵ′_(i), ŵ′_(n-1) and ŵ′_(n)represent a first encrypted bit value, a second encrypted bit value, ani th encrypted bit value, an n−1 th encrypted bit value and an n thencrypted bit value in Ŵ′; the values of ŵ′₁, ŵ′₂, ŵ′_(i), ŵ′_(n-1) andŵ′_(n) are 0 or 1; ŵ₁, ŵ₂, ŵ_(i), ŵ_(n-1) and ŵ_(n) represent a firstdecrypted bit value, a second decrypted bit value, an i th decrypted bitvalue, an n−1 th decrypted bit value and an n th decrypted bit value inŴ, the values of ŵ₁, ŵ₂, ŵ_(i), ŵ_(n-1) and ŵ_(n) are 0 or 1.

A process of obtaining an index of the pixel selected by the coding modeM_(org) ^(k) corresponding to the current CU after being embedded withthe hidden information by using w′_(i) to modulate the index of a pixelselected by coding mode M_(org) ^(k) corresponding to the current CUwhen encoding the current CU in step (1)_6e and step (1)_6 is markingthe index of the pixel selected by the coding mode M_(org) ^(k),corresponding to the current CU when encoding the current CU as I_(org)^(k), and marking the index of the pixel selected by the coding modeM_(org) ^(k), corresponding to the current CU after being embedded withhidden information as Ĩ_(org) ^(k),

${\overset{\sim}{I}}_{org}^{k} = \left\{ {\begin{matrix}{I_{org}^{k},} & {{{if}\mspace{14mu} I_{org}^{k}} = w_{i}^{\prime}} \\{w_{i}^{\prime},} & {{{if}\mspace{14mu} I_{org}^{k}} \neq w_{i}^{\prime}}\end{matrix}.} \right.$

In step (1)_6h, a corresponding mode range of a right above neighboringCU of the current CU is a prediction mode set which comprises a 0thprediction mode and prediction modes from a 2nd to a 10th or aprediction mode set generated by DMM (Depth Modeling Mode) modes; acorresponding mode range of a right neighboring CU of the current CU isa prediction mode set which comprises the 0th prediction mode andprediction modes from a 1st to a 25th or a prediction mode set generatedby DMM modes; a corresponding mode range of a right below neighboring CUof the current CU is a prediction mode set which comprises the 0th andthe 1st predication modes and prediction modes from a 11th to the 25thor a prediction mode set generated by DMM modes; a corresponding moderange of a left below neighboring CU of the current CU is a predictionmode set which comprises the 0th prediction mode and prediction modesfrom a 26th to a 34th or a prediction mode set generated by DMM modes; acorresponding mode range of a below neighboring CU of the current CU isa prediction mode set which comprises the 0th and 1st predication modesand prediction modes from the 11th to the 34th or a prediction mode setgenerated by DMM modes.

A process of parsing the index of the pixel selected by the coding modeM_(dec) ^(k) corresponding to the current CU after being embedded withhidden information and obtaining the i th bit value of the encrypted bitvalue ŵ′_(i) in step (2)_6e and step (2)_6h is marking the index of thepixel selected by the coding mode M_(dec) ^(k) corresponding to thecurrent CU after being embedded with hidden information as Ĩ_(dec) ^(k),

${\hat{w}}_{i}^{\prime} = \left\{ {\begin{matrix}{0,} & {{{if}\mspace{14mu} {\overset{\sim}{I}}_{dec}^{k}} = 0} \\{1,} & {{{if}\mspace{14mu} {\overset{\sim}{I}}_{dec}^{k}} = 1}\end{matrix}.} \right.$

In step (2)_6, a corresponding mode range of a right above neighboringCU of the current CU is a prediction mode set which comprises a 0thprediction mode and prediction modes from a 2nd to a 10th or aprediction mode set generated by DMM modes; a corresponding mode rangeof a right neighboring CU of the current CU is a prediction mode setwhich comprises the 0th prediction mode and prediction modes from a 1stto a 25th or a prediction mode set generated by DMM modes; acorresponding mode range of a right below neighboring CU of the currentCU is a prediction mode set which comprises the 0th and the 1stpredication modes and prediction modes from a 11th to the 25th or aprediction mode set generated by DMM modes; a corresponding mode rangeof a left below neighboring CU of the current CU is a prediction modeset which comprises the 0th prediction mode and prediction modes from a26th to a 34th or a prediction mode set generated by DMM modes; acorresponding mode range of a below neighboring CU of the current CU isa prediction mode set which comprises the 0th and 1st predication modesand prediction modes from the 11th to the 34th or a prediction mode setgenerated by DMM modes.

Comparing to the conventional technology, the advantage of the presentinvention lies in:

1) The present invention hides the information in compression domain of3D-HEVC depth video. The present invention uses the single-depth intramode which is designed for encoding the smooth region of the depth videoin 3D-HEVC coding standard to complete the embedment and extraction ofthe hidden information. Because the extension of H.264 on 3D video isnot equipped with single-depth intra mode, the present invention iscompletely different from the compression domain information hidingmethod of the extension of H.264 on 3D video.

2) The present invention generates a pseudo-random binary sequence usinglogistics chaos mapping as a key during information embedment. Thehidden information needing to be embedded is encrypted and the CU forthe embedment is positioned by using the key, which improves thesecurity of the present invention effectively.

3) The present invention constructs the pixel candidate list of thecoding mode of the CU the coding mode of which is single-depth intramode. If the two pixels in the candidate list are equal and theinformation bit value extracted from the key is 1, the index of thepixel of coding mode of the CU is modulated by using the information bitvalue extracted from the encrypted information; If the two pixels in thecandidate list are different and the depth of the CU is 2 or 3 and thecoding modes of the right neighboring CU and below neighboring CU arenot single-depth intra mode, whether to embed the hidden information inthe CU is decided by judging the prediction mode of the right aboveneighboring CU, right neighboring CU, right below neighboring CU, leftbelow neighboring CU and below CU of the current CU. In such a manner,drifting error is avoided in the hidden information embedment method.

4) In the information extraction part of the present invention, theencrypted information is able to be extracted blinded without theinvolvement of the original video, which reduces the calculationcomplexity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1a is a general flow chart of an information embedment part of thepresent invention;

FIG. 1b is a general flow chart of an information extraction part of thepresent invention;

FIG. 2a is a first frame of the 4^(th) viewpoint rendered from theBalloons stereo video stream without embedding hidden information;

FIG. 2b is a first frame of the 3^(rd) viewpoint rendered from theNewspaper stereo video stream without embedding hidden information;

FIG. 2c is a first frame of the 5^(th) viewpoint rendered from the Sharkstereo video stream without embedding hidden information;

FIG. 2d is a first frame of the 4^(th) viewpoint rendered from theBalloons stereo video stream embedded with hidden information throughthe present invention;

FIG. 2e is a first frame of the 3^(rd) viewpoint rendered from theNewspaper stereo video stream embedded with hidden information throughthe present invention;

FIG. 2f is a first frame of the 5^(th) viewpoint rendered from the Sharkstereo video stream embedded with hidden information through the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings, according to a preferred embodiment of thepresent invention is illustrated, wherein

The present invention provides a 3D-HEVC depth video information hidingmethod based on single-depth intra mode, comprises information embedmentand information extraction part.

The information embedment part of the present invention illustrated inFIG. 1a comprises the following steps of:

(1)_1, Let S_(org) represent an original 3D (three dimensional) video,L_(org) ^(c) represent a left view color video of S_(org), L_(org) ^(d),represent a left view depth video corresponding to L_(org) ^(c), R_(org)^(c) represent a right view color video of S_(org), R_(org) ^(d),represent a right view depth video corresponding to R_(org) ^(c);L_(org) ^(c), L_(org) ^(d) and R_(org) ^(c), or R_(org) ^(d) arecompressed and encoded through 3D-HEVC standard coding platform togenerate target video stream str.bin_(org); M and N denote widths andheights of frames in L_(org) ^(c), L_(org) ^(d), R_(org) ^(c) andR_(org) ^(d) respectively; The number of frames contained in the L_(org)^(c), L_(org) ^(d), R_(org) ^(c) and R_(org) ^(d) are same which is allF; W represents hidden information to be embedded, wherein W comprisesan n-bit value, W={w₁, w₂, . . . , w_(i), . . . , w_(n-1), w_(n)}, w₁,w₂, w_(i), w_(n-1) and w_(n) represent the first bit value, the secondbit value, the i-th bit value, the n−1-th bit value and the n-th bitvalue in W respectively; the values of w₁, w₂, w_(i), w_(n-1) and w_(n)are 0 or 1, 1≦i≦n,

$n \in {\left\lbrack {1,\frac{M \times N \times F}{8 \times 8}} \right\rbrack.}$

L_(org) ^(c), L_(org) ^(d), and R_(org) ^(c), R_(org) ^(d), are encodedin the following sequence, the first frame in the left view color videoL_(org) ^(c), the first frame in the left view depth video L_(org) ^(d),the first frame in the right view color video R_(org) ^(c), the firstframe of the right view depth video R_(org) ^(d), encoding is processedframe by frame until all frames in the L_(org) ^(c), L_(org) ^(d) andR_(org) ^(c), R_(org) ^(d) are encoded.

(1)_2, Uses logistics chaos mapping to generate a pseudo-random binarysequence that contains n bits value as a key E, E={e₁, e₂, . . . ,e_(i), . . . , e_(n-1), e_(n)}; wherein processes every bit value of Eand the corresponding bit value of W with XOR to generate encryptedinformation W′, W′={w′₁, w′₂, . . . , w′_(i), . . . , w′_(n-1), w′_(n)};initial information of the key E is given arbitrarily; e₁, e₂, e_(i),e_(n-1) and e_(n) represent a first bit value, a second bit value, ani-th bit value, an n−1-th bit value and an n-th bit value in Erespectively; the values of e₁, e₂, e_(i), e_(n-1) and e_(n) are 0 or 1;w′₁, w′₂, w′_(i), w′_(n-1) and w′_(n) represent a first bit value, asecond bit value, an i-th bit value, an n−1-th bit value and an n-th bitvalue in W′ respectively; the values of w′₁, w′₂, w′_(i), w′_(n-1) andw′_(n) are 0 or 1, 1≦i≦n;

(1)_3, Parses each frame of the target video stream str.bin_(org), setsa current frame needing to be parsed in the target video streamstr.bin_(org) as the current frame;

(1)_4, Determines whether the current frame is a left view depth frameor a right view depth frame, if yes go to step (1)_5 or else go to step(1)_8;

(1)_5, Parses each CTU (coding tree unit) of the current frame; Sets acurrent CTU needing to be parsed in the current frame as a current parseblock, then go to step (1)_6;

(1)_6, According to the optimal splitting mode of the current parseblock, parses every coding mode corresponding to CU (coding unit) in thecurrent parse block after being split. B_(org) ^(k) represents the k thCU in the current parse block; The corresponding coding mode of B_(org)^(k) is marked as M_(org) ^(k), k is a positive integer, kε[1, 64], thesize of the B_(org) ^(k) is 8×8, 16×16, 32×32 or 64×64, M_(org)^(k)ε{intra coding mode, single-depth intra coding mode}; then go to thefollowing steps:

(1)_6a, Sets the CU under processing of the current parse block as thecurrent CU;

(1)_6b, Assumes the current CU is B_(org) ^(k), if the coding modelM_(org) ^(k) corresponding to the current CU is an intra coding modethen go to step (1)_6i; otherwise, if the coding model M_(org) ^(k)corresponding to the current CU is a single-depth intra coding mode thengo to step (1)_6c;

(1)_6c, According to the coding theory of the single-depth intra codingmode constructs the pixel candidate list of the coding mode M_(org) ^(k)corresponding to the current CU and marked as list_(org) ^(k) whichcontains 2 pixels; a first pixel is marked as y_(org) ^(k,1) the indexof which is 0 and a second pixel is marked as y_(org) ^(k,2) the indexof which is 1, 0≦y_(org) ^(k,1)≦255, 0≦y_(org) ^(k,2)≦255; reads a valueof j th bit e_(j) in the key E and reads a value of i th bit w′_(i) inthe encrypted information W′, 1≦j≦n, an initial value of j is 1, 1≦i≦n,an initial value of i is 1; go to step (1)_6d;

(1)_6d, Determines whether y_(org) ^(k,1) equals y_(org) ^(k,2), if yes,go to step (1)_6e, if no, go to step (1)_6f;

(1)_6e, If e_(j) is 1, uses w′_(i) to modulate the index of a pixelselected by the coding mode M_(org) ^(k) corresponding to the current CUwhen encoding the current CU and gets an index of the pixel selected bythe coding mode M_(org) ^(k) corresponding to the current CU after beingembedded with hidden information when the current CU goes throughencoding, and then entropy-coding of the index of the pixel selected bythe coding mode M_(org) ^(k) corresponding to the current CU after beingembedded with hidden information when the current CU goes throughencoding; the embedment of the hidden information in the current CU iscompleted by now; j=j+1 and i=i+1, go to step (1)_6i; otherwise, ife_(j) is 0, then j=j+1, go to step (1)_6i; “=” is a assignment operatorin j=j+1 and i=+1;

In the embodiment, the process of obtaining an index of the pixelselected by the coding mode M_(org) ^(k) corresponding to the current CUafter being embedded with the hidden information by using w′_(i) tomodulate the index of a pixel selected by coding mode M_(org) ^(k)corresponding to the current CU when encoding the current CU in step(1)_6e is marking the index of the pixel selected by the coding modeM_(org) ^(k) corresponding to the current CU when encoding the currentCU as I_(org) ^(k) and marking the index of the pixel selected by thecoding mode M_(org) ^(k) corresponding to the current CU after beingembedded with hidden information as Ĩ_(org) ^(k),

${\overset{\sim}{I}}_{org}^{k} = \left\{ {\begin{matrix}{I_{org}^{k},} & {{{if}\mspace{14mu} I_{org}^{k}} = w_{i}^{\prime}} \\{w_{i}^{\prime},} & {{{if}\mspace{14mu} I_{org}^{k}} \neq w_{i}^{\prime}}\end{matrix}.} \right.$

(1)_6f, Parses a depth of the current CU, if the depth is 2 or 3 then goto (1)_6g; if the depth is 0 or 1, then go to step (1)_6i, depthε{0, 1,2, 3}

(1)_6g, Determines whether the coding mode of a right neighboring CU ora below neighboring CU is single-depth intra coding mode, if yes, go tostep (1)_6i, else, go to step (1)_6; the right neighboring CU is aneighboring CU which is on the right side of the current CU; the belowneighboring CU is a neighboring CU which is below the current CU;

(1)_6h, Determines whether a prediction mode of the right aboveneighboring CU, right neighboring CU, right below neighboring CU, leftbelow neighboring CU and below neighboring CU of the current CU belongsto a corresponding mode range respectively; if not, uses w′_(i) tomodulate the index of the pixel selected by coding mode M_(org) ^(k)corresponding to the current CU when encoding the current CU and gets anindex of the pixel selected by the coding mode M_(org) ^(k)corresponding to the current CU after being embedded with hiddeninformation when the current CU goes through encoding, and thenentropy-coding of the index of the pixel selected by the coding modeM_(org) ^(k) corresponding to the current CU after being embedded withhidden information when the current CU goes through encoding; theembedment of the hidden information in the current CU is completed bynow; i=i+1, go to step (1)_6i; else, go to step (1)_6i; the right aboveneighboring CU is a neighboring CU which is above and on the right sideof the current CU; the right below neighboring CU is a neighboring CUwhich is below and on the right side of the current CU; the left belowneighboring CU is a neighboring CU which is below and on the left sideof the current CU;

In the embodiment, a corresponding mode range of a right aboveneighboring CU of the current CU is a prediction mode set whichcomprises a 0th prediction mode and prediction modes from a 2nd to a10th or a prediction mode set generated by DMM (Depth Modeling Mode)modes; a corresponding mode range of a right neighboring CU of thecurrent CU is a prediction mode set which comprises the 0th predictionmode and prediction modes from a 1st to a 25th or a prediction mode setgenerated by DMM modes; a corresponding mode range of a right belowneighboring CU of the current CU is a prediction mode set whichcomprises the 0th and the 1st predication modes and prediction modesfrom a 11th to the 25th or a prediction mode set generated by DMM modes;a corresponding mode range of a left below neighboring CU of the currentCU is a prediction mode set which comprises the 0th prediction mode andprediction modes from a 26th to a 34th or a prediction mode setgenerated by DMM modes; a corresponding mode range of a belowneighboring CU of the current CU is a prediction mode set whichcomprises the 0th and 1st predication modes and prediction modes fromthe 11th to the 34th or a prediction mode set generated by DMM modes.

the process of obtaining an index of the pixel selected by the codingmode M_(org) ^(k) corresponding to the current CU after being embeddedwith the hidden information by using w′_(i) to modulate the index of apixel selected by coding mode M_(org) ^(k) corresponding to the currentCU when encoding the current CU in step (1)_6 is marking the index ofthe pixel selected by the coding mode M_(org) ^(k) corresponding to thecurrent CU when encoding the current CU as I_(org) ^(k) and marking theindex of the pixel selected by the coding mode M_(org) ^(k)corresponding to the current CU after being embedded with hiddeninformation as Ĩ_(org) ^(k),

${\overset{\sim}{I}}_{org}^{k} = \left\{ {\begin{matrix}{I_{org}^{k},} & {{{if}\mspace{14mu} I_{org}^{k}} = w_{i}^{\prime}} \\{w_{i}^{\prime},} & {{{if}\mspace{14mu} I_{org}^{k}} \neq w_{i}^{\prime}}\end{matrix}.} \right.$

(1)_6i, Sets a next CU needing to be processed of the current parseblock as the current CU and go back to step (1)_6b. Move on until theprocessing of all the CU in the current parse block is completed andthen go to step (1)_7;

(1)_7, Sets the next CTU needing to be parsed of the current frame asthe current parse block and go back to step (1)_6; moves on until theprocessing of all the CTU in the current frame is completed and then goto step (1)_8;

(1)_8, Sets the next frame needing to be parsed in the target videostream str.bin_(org) as the current frame and go back to step (1)_4;moves on until the processing of all the frames in the target videostream str.bin_(org) is completed and obtains the video streamstr.bin_(dec) which embedded with the hidden information;

(1)_9, Transmits the information of initial value which generates thekey E to an information extraction terminal, with which the same key Eis able to be generated at the information extraction terminal.

an information extraction method comprises following steps asillustrated in FIG. 1 b:

(2)_1, sets the video stream which embedded with the hidden informationas the target video stream str.bin_(dec);

(2)_2, according to the information of the initial value which generatesthe key E transmitted from the information embedment terminal, generatesa same key E using logistics chaos mapping. If the key E generated atthe information embedment terminal is directly transmitted to theinformation extraction terminal, the side-information is too big.Because the process to generate the key E is simple, and with the sameinitial value the same key E is able to be re-generated, onlytransmitting the initial value to the information extraction terminal isenough so as to reduce the amount of side-information;

(2)_3, Parses each frame of the target video stream str.bin_(dec) andsets a current frame needing to be parsed in the target video streamstr.bin_(dec) as a current frame;

(2)_4, Determines whether the current frame is the left view depth imageor the right view depth image; if yes, go to step (2)_5, else, go tostep (2)_8;

(2)_5, Parses the current frame by the CTU and sets the current CTUneeding to be parsed in the current frame as current parse block, thengo to step (2)_6;

(2)_6, According to the optimal splitting mode of the current parseblock, parses every coding mode corresponding to the CU in the currentparse block after being split. B_(dec) ^(k) represents the k th CU inthe current parse block; The corresponding coding mode of B_(dec) ^(k)is marked as M_(dec) ^(k), k is an positive integer, kε[1, 64], the sizeof the B_(dec) ^(k) is 8×8, 16×16, 32×32 or 64×64, M_(dec) ^(k)ε{intracoding mode, single-depth intra coding mode}; then go to the followingsteps:

(2)_6a, Sets the CU under processing of the current parse block as thecurrent CU;

(2)_6b, Assumes the current CU is B_(dec) ^(k), if the coding modelM_(dec) ^(k) corresponding to the current CU is the intra coding modethen go to step (2)_6i; if the coding model M_(dec) ^(k) correspondingto the current CU is single-depth intra coding mode then go to step(2)_6c;

(2)_6c, According to the coding theory of the single-depth intra codingmode constructs the pixel candidate list of the coding mode M_(dec) ^(k)corresponding to the current CU and marked as list_(dec) ^(k) whichcontains 2 pixels; a first pixel is marked as y_(dec) ^(k,1) and asecond pixel is marked as y_(dec) ^(k,2), 0≦y_(dec) ^(k,1)≦255,0≦y_(dec) ^(k,2)≦255; reads a value of the j th bit e_(j) in the key E,1≦j≦n, an initial value of j is 1, go to step (2)_6d;

(2)_6d, Determines whether y_(dec) ^(k,1) equals y_(dec) ^(k,2), if yes,go to step (2)_6e, if no, go to step (2)_6f;

(2)_6e, If e_(j) is 1, parses the index of a pixel selected by thecoding mode M_(dec) ^(k) corresponding to the current CU after beingembedded with hidden information and gets the i th bit value of theencrypted information ŵ′_(i), the extraction of the hidden informationin the current CU is completed by now; j=j+1 and i=i+1, go to step(2)_6i; if e_(j) is 0, then j=j+1, go to step (2)_6i; 1≦i≦n, the initialvalue of i is 1, ŵ′_(i) is 0 or 1, “=” is a assignment operator in j=j+1and i=i+1;

In the embodiment, a process of parsing the index of the pixel selectedby the coding mode M_(dec) ^(k) corresponding to the current CU afterbeing embedded with hidden information and obtaining the i th bit valueof the encrypted bit value ŵ′_(i) in step (2)_6e is marking the index ofthe pixel selected by the coding mode M_(dec) ^(k) corresponding to thecurrent CU after being embedded with hidden information as Ĩ_(dec) ^(k),

${\hat{w}}_{i}^{\prime} = \left\{ {\begin{matrix}{0,} & {{{if}\mspace{14mu} {\overset{\sim}{I}}_{dec}^{k}} = 0} \\{1,} & {{{if}\mspace{14mu} {\overset{\sim}{I}}_{dec}^{k}} = 1}\end{matrix}.} \right.$

(2)_6f, Resolves a depth of the current CU, if the depth is 2 or 3 thengo to step (2)_6g; if the depth is 0 or 1, then go to step (2)_6i,depthε{0, 1, 2, 3};

(2)_6g, Determines whether the coding mode of a right neighboring CU ora below neighboring CU is the single-depth intra coding mode, if yes, goto step (2)_6i, else, go to step (2)_6; the right neighboring CU is aneighboring CU which is on the right side of the current CU; the belowneighboring CU is a neighboring CU which is below the current CU;

(2)_6h, Determines whether a prediction mode of the right aboveneighboring CU, right neighboring CU, right below neighboring CU, leftbelow neighboring CU and below neighboring CU of the current CU belongsto a corresponding mode range respectively; if not, parses the index ofa pixel selected by the coding mode M_(dec) ^(k) corresponding to thecurrent CU after being embedded with hidden information and gets the ith bit value of the encrypted information ŵ′_(i), the extraction of thehidden information in the current CU is completed by now; i=i+1, go tostep (2)_6i; else, go to step (2)_6i; the right above neighboring CU isa neighboring CU which is above and on the right side of the current CU;the right below neighboring CU is a neighboring CU which is below and onthe right side of the current CU; the left below neighboring CU is aneighboring CU which is below and on the left side of the current CU;

In the embodiment, a corresponding mode range of a right aboveneighboring CU of the current CU is a prediction mode set whichcomprises a 0th prediction mode and prediction modes from a 2nd to a10th or a prediction mode set generated by DMM modes; a correspondingmode range of a right neighboring CU of the current CU is a predictionmode set which comprises the 0th prediction mode and prediction modesfrom a 1st to a 25th or a prediction mode set generated by DMM modes; acorresponding mode range of a right below neighboring CU of the currentCU is a prediction mode set which comprises the 0th and the 1stpredication modes and prediction modes from a 11th to the 25th or aprediction mode set generated by DMM modes; a corresponding mode rangeof a left below neighboring CU of the current CU is a prediction modeset which comprises the 0th prediction mode and prediction modes from a26th to a 34th or a prediction mode set generated by DMM modes; acorresponding mode range of a below neighboring CU of the current CU isa prediction mode set which comprises the 0th and 1st predication modesand prediction modes from the 11th to the 34th or a prediction mode setgenerated by DMM modes.

A process of parsing the index of the pixel selected by the coding modeM_(dec) ^(k) corresponding to the current CU after being embedded withhidden information and obtaining the i th bit value of the encrypted bitvalue ŵ′_(i) in step (2)_6 is marking the index of the pixel selected bythe coding mode M_(dec) ^(k) corresponding to the current CU after beingembedded with hidden information as Ĩ_(dec) ^(k),

${\hat{w}}_{i}^{\prime} = \left\{ {\begin{matrix}{0,} & {{{if}\mspace{14mu} {\overset{\sim}{I}}_{dec}^{k}} = 0} \\{1,} & {{{if}\mspace{14mu} {\overset{\sim}{I}}_{dec}^{k}} = 1}\end{matrix}.} \right.$

(2)_6i, Sets a next CU needing to be processed in the current parseblock as the current CU and go back to step (2)_6b. Move on until theprocess of all the CU in the current parse block is completed and thengo to step (2)_7;

(2)_7, Sets the next CTU needing to be parsed of the current frame asthe current parse block and go back to step (2)_6; move on until theprocess of all the CTU in the current frame is completed and then go tostep (2)_8;

(2)_8, Sets the next frame needing to be parsed in the target videostream str.bin_(dec) as the current frame and go back to step (2)_4;move on until the process of all the frames in the target video streamstr.bin_(dec) is completed and the extraction of the hidden informationis completed;

(2)_9, gets n bit values of encrypted information and constructs theencrypted information Ŵ′, Ŵ′={ŵ′₁, ŵ′₂, . . . , ŵ′_(i), . . . ,ŵ′_(n-1), ŵ′_(n)}; processes every bit value of the encryptedinformation of Ŵ′ and the corresponding bit value of the key E with XORand generates the decrypted information Ŵ, Ŵ={ŵ₁, ŵ₂, . . . , ŵ_(i), . .. , ŵ_(n-1), ŵ_(n)}; w′₁, w′₂, w′_(i), w′_(n-1) and w′_(n) and representthe first encrypted bit value, the second encrypted bit value, the i thencrypted bit value, the n−1 th encrypted bit value and the n thencrypted bit value in Ŵ′; the values of w′₁, w′₂, w′_(i), w′_(n-1) andw′_(n) are 0 or 1; ŵ₁, ŵ₂, ŵ_(i), ŵ_(n-1) and ŵ_(n) represent a firstdecrypted bit value, a second decrypted bit value, an i th decrypted bitvalue, an n−1 th decrypted bit value and an n th decrypted bit value inŴ, the values of ŵ′₁, ŵ′₂, ŵ′_(i), ŵ′_(n-1) and ŵ′_(n) are 0 or 1.

In order to test the effectiveness and feasibility of the presentinvention the following experiment is carried out:

The adopted test sequences are the 3^(rd) and 5^(th) viewpoints ofBalloons stereo video sequence, the 2^(nd) and 4^(th) viewpoints ofNewspaper stereo video, the 3^(rd) and 5^(th) viewpoint of Kendo stereovideo, the 1^(st) and 9^(th) viewpoints of Shark stereo video, the3^(rd) and 5^(th) viewpoints of PoznanStreet stereo video and the 1^(st)and 9^(th) viewpoints of UndoDancer stereo video. Resolution of thefirst three of the sequence is 1024×768 and the last three is 1920×1088.HTM13.0 is adopted as the test software which is the coding platformbased on 3D-HEVC standard. Use All-intra profile to encode 100 frames.The encoding QP (quantization parameter) of the color video is 25, 30,35 and 40 while QP of the corresponding depth video is 34, 39, 42 and45. Other configuration parameters are the default value of theplatform. Below is an evaluation of the performance of the presentinvention on aspect of embedding capacity, bit rate, theimperceptibility of the stereo video sequence and etc.

1) Embedding Capacity and Bitrate Change

The embedding capacity and bitrate change is the main indicator for theperformance of the information hiding method. Table 1 shows the testresult of the embedding capacity and bitrate change of the presentinvention being applied to Balloons, Newspaper, Kendo, Shark,PoznanStreet and UndoDancer stereo video sequences. Table 1 gives themeans of the embedding capacity of all the depth frames. The bitratechange BRI is defined as

${{BRI} = {\frac{R_{pro} - R_{org}}{R_{org}} \times 100\%}},$

wherein R_(pro) represents the bitrate of the encoded video streamprocessed with the present invention and R_(org) is the bitrate of theoriginal encoded video stream.

The embedding capacity is related to resolution of the stereo videosequence and QP of the encoding. The embedding capacity is proportionalto the resolution while is inversely proportional to the QP. Higherresolution indicates more CU which is able to be embedding carrier.Increased QP influences the selection of the optimal splitting mode andthus has big influence on rate distortion of the encoding. The averageembedding capacity per frame of depth image is 244 bit under all the QP.The change rate of the bit rate of the stereo video sequence is0.03%-0.25% before and after the information embedment. The averagechange rate is 0.12% which indicates that the embedding capacity of thepresent invention is high and the present invention has small influenceon the bitrate.

TABLE 1 Test result of the embedding capacity and bit rate change rateof the present invention Embedding Bitrate (kbps) Stereo video capacityOriginal The present Change sequence Resolution QP (bit/frame) encodinginvention rate Balloons 1024 × 768  25 348 15786.019 15807.365 0.14% 30172 9688.238 9701.158 0.13% 35 102 5934.821 5943.029 0.14% 40 603639.576 3644.455 0.13% Newspaper 1024 × 768  25 396 23593.044 23614.8530.09% 30 237 13293.386 13309.423 0.12% 35 160 7607.429 7619.117 0.15% 40100 4392.242 4399.615 0.17% Kendo 1024 × 768  25 263 10189.21 10207.3060.18% 30 103 6132.725 6141.086 0.14% 35 54 3721.435 3725.902 0.12% 40 372297.899 2300.882 0.13% Shark 1920 × 1088 25 803 53949.878 54032.4360.15% 30 554 30434.542 30488.789 0.18% 35 358 15916.339 15949.505 0.21%40 227 7851.662 7871.249 0.25% PoznanStreet 1920 × 1088 25 551 47256.647280.99 0.05% 30 210 23110.58 23120.44 0.04% 35 121 11800.81 11807.510.06% 40 66 6325.92 6328.334 0.04% UndoDancer 1920 × 1088 25 31473108.164 73129.024 0.03% 30 250 37428.284 37446.912 0.05% 35 19816872.418 16886.584 0.08% 40 177 7130.218 7139.852 0.13%

2) The Imperceptibility of the Stereo Video Sequence

The imperceptibility is another performance indicator of the informationhiding method for the stereo video, which indicates whether there is anobvious decline in quality of the stereo video after embedding theinformation. The depth video is not for directly view, but for virtualview point rendering. So a change in the quality of depth video afterembedding is able to be displayed by the quality of the renderedviewpoint. Taking Balloons, Newspaper and Shark stereo video sequencesas an example, FIG. 2a shows the first frame of the 4^(th) viewpointrendered with the decoded 3^(rd) and 5^(th) viewpoints of the Balloonsstereo video sequence without embedding hidden information. FIG. 2bshows the first frame of the 3^(rd) viewpoint rendered with the decoded2^(nd) and 4^(th) viewpoints of the Newspaper stereo video sequencewithout embedding hidden information. FIG. 2c shows the first frame ofthe 5^(th) viewpoint rendered with the decoded 1^(st) and 9^(th)viewpoints of the Shark stereo video sequence without embedding hiddeninformation. FIG. 2d gives the first frame of the 4^(th) viewpointrendered with the decoded 3^(rd) and 5^(th) viewpoints of the Balloonsstereo video sequence embedded hidden information with the presentinvention. FIG. 2e gives the first frame of the 3^(rd) viewpointrendered with the decoded 2^(nd) and 4^(th) viewpoints of the Newspaperstereo video sequence embedded hidden information with the presentinvention. FIG. 2f gives the first frame of the 5^(th) viewpointrendered with the decoded 1^(st) and 9^(th) viewpoints of the Sharkstereo video sequence embedded hidden information with the presentinvention. Comparing FIG. 2a with FIG. 2d , FIG. 2b with FIG. 2e andFIG. 2c with FIG. 2f there is no obviously rendering viewpointdistortion after embedding the hidden information, which proves that theimperceptibility of the present invention is good.

In addition to the subjective assessment, the change in quality of thestereo video before and after the embedding is able to be evaluated byobjective assessment. PSNR (Peak Signal-Noise-Ratio) and SSIM(Structural similarity index) are adopted here. Table 2 gives the PSNRsand SSIMs of the viewpoints rendered with the decoded stereo videosequences which have been embedded with hidden information by thepresent invention, as well as the PSNRs and SSIMs of the viewpointsrendered with the decoded stereo video sequences without embeddinghidden information. The formula for variation of PSNR and SSIM beforeand after embedding the hidden information ΔPSNR and ΔSSIM isΔPSNR=PSNR_(pro)−PSNR_(org) and ΔSSIM=SSIM_(pro)−SSIM_(org)respectively. PSNR_(pro) and SSIM_(pro) represent the PSNR and SSIMbetween original viewpoint and the viewpoint rendering from the stereovideo sequence generated by decoded video stream processed by thepresent invention, respectively. PSNR_(org) and SSIM_(org) represent thePSNR and SSIM between original viewpoint and the viewpoint renderingfrom the stereo video sequence generated by decoded video stream. Theexperiment evaluates the imperceptibility of the stereo video by thevalue of ΔPSNR and ΔSSIM.

Table 2 shows the quality of the viewpoint rendering from the decodedstereo video sequence varies under different QP. The higher QP resultsthe lower quality of the rendered viewpoint, because the increase in QPcauses higher compression which induce high distortion level and lowquality of viewpoint rendering. The variation of absolute value of PSNRof the viewpoint rendered with stereo video sequence which is decodedfrom the video stream before and after the embedding is within 0˜0.0139dB. The PSNR of the rendered viewpoint is reduced an average 0.00141 dBafter being processed by the present invention comparing to the videostream not processed by the present invention, which proves that theinfluence of the present invention on the quality of the renderedviewpoint is slight. The PSNR may differ from the subjective perceptionso Table 2 also lists SSIM. The SSIM of the rendered viewpoint isreduced an average 0.000006 after being processed by the presentinvention comparing to the video stream not processed by the presentinvention, which further indicates the present invention has goodimperceptibility for the stereo video. When the pixels in the candidatelist of the single-depth intra coding mode of the CU are equal, thepresent invention adopts the hidden information to modulate the index ofthe pixels in the candidate list which will not cause any distortion forthe current CU. When the pixels in the candidate list of thesingle-depth intra coding mode of the CU are different, the presentinvention only distorts the current CU because drift error is taken intoaccount.

TABLE 2 PSNR and SSIM of the rendered viewpoints generated with thevideo stream being processed by the present invention comparing to thevideo stream without hidden information Stereo video PSNR(dB) SSIMsequence QP PSNR_(pro) PSNR_(org) ΔPSNR SSIM_(pro) SSIM_(org) ΔSSIMBalloons 25 35.8779 35.8788 −0.0009 0.967303 0.967305 −0.000002 3035.4895 35.5034 −0.0139 0.962719 0.962765 −0.000046 35 34.778 34.7798−0.0018 0.953266 0.95327 −0.000004 40 33.5025 33.5038 −0.0013 0.935470.935475 −0.000005 Newspaper 25 31.999 32.0011 −0.0021 0.936266 0.936284−0.000018 30 31.8229 31.8233 −0.0004 0.928699 0.928705 −0.000006 3531.4768 31.4793 −0.0025 0.914362 0.914386 −0.000024 40 30.7325 30.7325 00.892702 0.892703 −0.000001 Kendo 25 38.4738 38.474 −0.0002 0.9736110.973612 −0.000001 30 38.0236 38.0236 0 0.970532 0.970533 −0.000001 3537.1934 37.1934 0 0.964527 0.964526 0.000001 40 35.8185 35.8186 −0.00010.954073 0.954073 0 Shark 25 41.23 41.2302 −0.0002 0.978532 0.978533−0.000001 30 39.127 39.1272 −0.0002 0.966029 0.96603 −0.000001 3536.4303 36.4304 −0.0001 0.942252 0.942253 −0.000001 40 33.638 33.6382−0.0002 0.90372 0.903722 −0.000002 PoznanStreet 25 35.4596 35.4596 00.928579 0.92858 −0.000001 30 35.1546 35.1548 −0.0002 0.914319 0.914321−0.000002 35 34.2796 34.2894 −0.0098 0.88978 0.889801 −0.000021 4032.8565 32.8565 0 0.857639 0.857639 0 UndoDancer 25 36.9156 36.9156 00.955244 0.955244 0 30 35.0647 35.0647 0 0.919827 0.919827 0 35 32.724532.7245 0 0.860651 0.860651 0 40 30.393 30.393 0 0.800526 0.800526 0

One skilled in the art will understand that the embodiment of thepresent invention as shown in the drawings and described above isexemplary only and not intended to be limiting.

It will thus be seen that the objects of the present invention have beenfully and effectively accomplished. Its embodiments have been shown anddescribed for the purposes of illustrating the functional and structuralprinciples of the present invention and is subject to change withoutdeparture from such principles. Therefore, this invention includes allmodifications encompassed within the spirit and scope of the followingclaims.

What is claimed is:
 1. A 3D-HEVC (3-Dimensional extension of HighEfficiency Video Coding) depth video information hiding method based onsingle-depth intra mode, comprising information embedment andinformation extraction; wherein, steps for the information embedment areas follow: (1)_1, representing an original 3D (three dimensional) videoby S_(org), denoting a left view color video of S_(org) as L_(org) ^(c),denoting a left view depth video corresponding to L_(org) ^(c) asL_(org) ^(d), denoting a right view color video of S_(org) as R_(org)^(c), denoting a right view depth video corresponding to R L_(org) ^(c)as R_(org) ^(d); wherein L_(org) ^(c), L_(org) ^(d) and R_(org) ^(c),R_(org) ^(d) are compressed and encoded through a 3D-HEVC standardcoding platform to generate a target video stream str.bin_(org); M and Ndenote widths and heights of frames in L_(org) ^(c), L_(org) ^(d),R_(org) ^(c) and R_(org) ^(d) respectively; F denotes the number offrames contained in the L_(org) ^(c), L_(org) ^(d), R_(org) ^(c) orR_(org) ^(d); W represents hidden information to be embedded, wherein Wcomprises an n-bit value, W={w₁, w₂, . . . , w_(i), . . . , w_(n-1),w_(n)}, w₁, w₂, w_(i), w_(n-1), w_(n) represent a first bit value, asecond bit value, an i-th bit value, an n−1-th bit value and an n-th bitvalue in W respectively; values of w₁, w₂, w_(i), w_(n-1) and w_(n) are0 or 1, 1≦i≦n,${n \in \left\lbrack {1,\frac{M \times N \times F}{8 \times 8}} \right\rbrack};$(1)_2, using logistics chaos mapping to generate a pseudo-random binarysequence that contains n bits value as a key E, E={e₁, e₂, . . . ,e_(i), . . . , e_(n-1), e_(n)}; processing every bit value of E and thecorresponding bit value of W with XOR to generate encrypted informationW′, W′={w′₁, w′₂, . . . , w′_(i), . . . , w′_(n-1), w′_(n)}; whereininitial information of the key E is given arbitrarily; e₁, e₂, e_(i),e_(n-1) and e_(n) represent a first bit value, a second bit value, ani-th bit value, an n−1-th bit value and an n-th bit value in Erespectively; the values of e₁, e₂, e_(i), e_(n-1) and e_(n) are 0 or 1;w′₁, w′₂, w′_(i), w′_(n-1) and w′_(n) represent a first bit value, asecond bit value, an i-th bit value, an n−1-th bit value and an n-th bitvalue in W′ respectively; the values of w′₁, w′₂, w′_(i), w′_(n-1) andw′_(n) are 0 or 1, 1≦i≦n; (1)_3, parsing each frame of the target videostream str.bin_(org) and setting a current frame needing to be parsed inthe target video stream str.bin_(org) as a current frame; (1)_4,determining whether the current frame is a left view depth frame or aright view depth frame, if yes executing step (1)_5 or else step (1)_8;(1)_5, parsing each CTU (coding tree unit) of the current frame andsetting a current CTU needing to be parsed in the current frame as acurrent parse block, then executing step (1)_6; (1)_6 according to anoptimal splitting mode of the current parse block, parsing every codingmode corresponding to CU (coding unit) in the current parse block afterbeing split; representing a k th CU in the current parse block byB_(org) ^(k); wherein a corresponding coding mode of B_(org) ^(k), ismarked as M_(org) ^(k), k is a positive integer, kε[1,64]; a size of theB_(org) ^(k) is 8×8, 16×16, 32×32 or 64×64, M_(org) ^(k)ε{intra codingmode, single-depth intra coding mode}; executing the following steps of:(1)_6a, setting a CU under processing in the current parse block as acurrent CU; (1)_6b, assuming the current CU is B_(org) ^(k), wherein ifthe coding model M_(org) ^(k), corresponding to the current CU is anintra coding mode then executing step (1)_6i; if the coding modelM_(org) ^(k), corresponding to the current CU is a single-depth intracoding mode then executing step (1)_6c; (1)_6c, according to a codingtheory of a single-depth intra coding mode, constructing a pixelcandidate list of the coding mode M_(org) ^(k) corresponding to thecurrent CU, which is marked as list_(org) ^(k); wherein list_(org) ^(k)contains 2 pixels; a first pixel is marked as y_(org) ^(k,1), an indexof which is 0; and a second pixel is marked as y_(org) ^(k,2), an indexof which is 1, 0≦y_(org) ^(k,1)≦255, 0≦y_(org) ^(k,2)≦255; reading avalue e_(j) of a j th bit in the key E and a value w′_(i) of an i th bitfrom the encrypted information W′; wherein 1≦j≦n, an initial value of jis 1, 1≦i≦n, a initial value of i is 1; executing step (1)_6d; (1)_6d,determining whether y_(org) ^(k,1) equals to y_(org) ^(k,2), if yes,executing step (1)_6e, else, executing step (1)_6f; (1)_6e, if e_(j) is1, using w′_(i) to modulate an index of a pixel selected by the codingmode M_(org) ^(k) corresponding to the current CU when encoding thecurrent CU and obtaining an index of the pixel after being embedded withhidden information when the current CU goes through encoding;entropy-coding the index of the pixel selected by the coding modeM_(org) ^(k) corresponding to the current CU after being embedded withthe hidden information when the current CU goes through encoding;completing embedment of the hidden information in the current CU; thenj=j+1 and i=i+1, executing step (1)_6i; otherwise, if e is 0, thenj=j+1, executing step (1)_6i; wherein “=” is an assignment operator inj=j+1 and i=i+1; (1)_6f, parsing a depth of the current CU, if the depthis 2 or 3 then executing step (1)_6g; if the depth is 0 or 1, thenexecuting step (1)_6i, depthε{0, 1, 2, 3}; (1)_6g, determining whether acoding mode of a right neighboring CU or a below neighboring CU is thesingle-depth intra coding mode, if yes, executing step (1)_6i, else,executing step (1)_6; wherein the right neighboring CU is a neighboringCU which is on a right side of the current CU; the below neighboring CUis a neighboring CU which is below the current CU; (1)_6h; determiningwhether a prediction mode of a right above neighboring CU, the rightneighboring CU, a right below neighboring CU, a left below neighboringCU and the below neighboring CU of the current CU belongs to acorresponding mode range respectively; if not, using w′_(i) to modulatethe index of the pixel selected by the coding mode M_(org) ^(k),corresponding to the current CU when encoding the current CU andobtaining the index of the pixel after being embedded with the hiddeninformation when the current CU goes through encoding; entropy-codingthe index of the pixel selected by the coding mode M_(org) ^(k),corresponding to the current CU after being embedded with the hiddeninformation when the current CU goes through encoding; completing theembedment of the hidden information in the current CU; i=i+1, executingstep (1)_6i; else, executing step (1)_6i; wherein the right aboveneighboring CU is a neighboring CU which is above and on the right sideof the current CU; the right below neighboring CU is a neighboring CUwhich is below and on the right side of the current CU; the left belowneighboring CU is a neighboring CU which is below and on a left side ofthe current CU; (1)_6i, setting a next CU needing to be processed of thecurrent parse block as the current CU and executing step (1)_6b; movingon until a process of all the CU in the current parse block is completedand then executing step (1)_7; (1)_7, setting a next CTU needing to beparsed of the current frame as a current parse block and executing step(1)_6; moving on until a process of all the CTU in a current frame iscompleted and then executing step (1)_8; (1)_8, setting a next frameneeding to be parsed in the target video stream str.bin_(org) as acurrent frame and executing step (1)_4; moving on until a process of allthe frames in the target video stream str.bin_(org) is completed andobtaining a video stream str.bin_(dec) which embedded with the hiddeninformation; (1)_9, transmitting information of an initial value whichgenerates the key E to an information extraction terminal; aninformation extraction method comprising following steps of: (2)_1,setting the video stream which embedded with the hidden information asthe target video stream str.bin_(dec); (2)_2, according to theinformation of the initial value which generates the key E transmittedfrom an information embedment terminal, generating a same key E usinglogistics chaos mapping; (2)_3, parsing each frame of the target videostream str.bin_(dec) and setting a current frame needing to be parsed inthe target video stream str.bin_(dec) as a current frame; (2)_4,determining whether the current frame is the left view depth image orthe right view depth image; if yes, executing step (2)_5, else,executing step (2)_8; (2)_5, parsing the current frame by the CTU andsetting the current CTU needing to be parsed in the current frame as acurrent parse block; then executing step (2)_6; (2)_6, according to anoptimal splitting mode of the current parse block, parsing every codingmode corresponding to the CU in the current parse block after beingsplit; representing a k th CU in the current parse block by B_(dec)^(k); wherein a corresponding coding mode of B_(dec) ^(k) is marked asM_(dec) ^(k), k is a positive integer, kε[1,64]; a size of the B_(dec)^(k) is 8×8, 16×16, 32×32 or 64×64, M_(dec) ^(k)ε{intra coding mode,single-depth intra coding mode}; then executing following steps of:(2)_6a, setting a CU under processing of the current parse block as acurrent CU; (2)_6b, assuming the current CU is B_(dec) ^(k); wherein ifthe coding model M_(dec) ^(k) corresponding to the current CU is theintra coding mode then go to step (2)_6i; if the coding model M_(dec)^(k) corresponding to the current CU is the single-depth intra codingmode then go to step (2)_6c; (2)_6c, according to the coding theory ofthe single-depth intra coding mode constructing a pixel candidate listwhich is marked as list_(dec) ^(k) of the coding mode M_(dec) ^(k)corresponding to the current CU; wherein list_(dec) ^(k) contains 2pixels; a first pixel is marked as y_(dec) ^(k,1) and a second pixel ismarked as y_(dec) ^(k,2), 0≦y_(dec) ^(k,1)≦255, 0≦y_(dec) ^(k,2)≦255;reading a value of a j th bit e_(j) in the key E, 1≦j≦n, wherein aninitial value of j is 1; executing step (2)_6d; (2)_6d, determiningwhether y_(dec) ^(k,1) is equal to y_(dec) ^(k,2), if yes, executingstep (2)_6e, else, executing step (2)_6f; (2)_6e, if e_(j) is 1, parsingan index of a pixel selected by the coding mode M_(dec) ^(k)corresponding to the current CU after being embedded with hiddeninformation and obtaining an i th bit value of the encrypted informationŵ′_(i); completing an extraction of the hidden information in thecurrent CU; j=j+1 and i=i+1, executing step (2)_6i; otherwise, if e_(j)is 0, then j=j+1, executing step (2)_6i; wherein 1≦i≦n, an initial valueof i is 1, ŵ′_(i) is 0 or 1, “=” is a assignment operator in j=j+1 andi=i+1; (2)_6f, parsing a depth of the current CU, if the depth is 2 or 3then executing step (2)_6g; if the depth is 0 or 1, then executing step(2)_6i, depthε{0, 1, 2, 3}; (2)_6g, determining whether a coding mode ofa right neighboring CU or a below neighboring CU is the single-depthintra coding mode, if yes, executing step (2)_6i, else, executing step(2)_6; wherein the right neighboring CU is a neighboring CU which is onthe right side of the current CU; the below neighboring CU is aneighboring CU which is below the current CU; (2)_6h, determiningwhether a prediction mode of a right above neighboring CU, the rightneighboring CU, a right below neighboring CU, a left below neighboringCU and the below neighboring CU of the current CU belongs to acorresponding mode range respectively; if not, parsing an index of apixel selected by the coding mode M_(dec) ^(k) corresponding to thecurrent CU after being embedded with the hidden information andobtaining an i th bit value of the encrypted information ŵ′_(i);completing an extraction of the hidden information in the current CU;i=i+1, executing step (2)_6i; else, executing step (2)_6i; wherein theright above neighboring CU is a neighboring CU which is above and on theright side of the current CU; the right below neighboring CU is aneighboring CU which is below and on the right side of the current CU;the left below neighboring CU is a neighboring CU which is below and onthe left side of the current CU; (2)_6i, setting a next CU needing to beprocessed in the current parse block as a current CU and executing step(2)_6b; moving on until a process of all the CU in the current parseblock is completed and then executing step (2)_7; (2)_7, setting a nextCTU needing to be parsed of the current frame as a current parse blockand executing step (2)_6; moving on until a process of all the CTU inthe current frame is completed and then executing step (2)_8; (2)_8,setting a next frame needing to be parsed in the target video streamstr.bin_(dec) as the current frame and executing step (2)_4; moving onuntil a process of all the frames in the target video streamstr.bin_(dec) is completed and completing the extraction of the hiddeninformation; (2)_9, obtaining n bit values of encrypted information andconstructing an encrypted information Ŵ′, Ŵ′{ŵ′₁, ŵ′₂, . . . , ŵ′_(i), .. . , ŵ′_(n-1), ŵ′_(n)}; processing every bit value of the encryptedinformation of Ŵ′ and the corresponding bit value of the key E with XORand generating the decrypted information Ŵ, Ŵ={ŵ₁, ŵ₂, . . . , ŵ_(i), .. . , ŵ_(n-1), ŵ_(n)}; wherein ŵ′₁, ŵ′₂, ŵ′_(i), ŵ′_(n-1) and ŵ′_(n)represent a first encrypted bit value, a second encrypted bit value, ani th encrypted bit value, an n−1 th encrypted bit value and an n thencrypted bit value in Ŵ′; the values of ŵ′₁, ŵ′₂, ŵ′_(i), ŵ′_(n-1) andŵ′_(n) are 0 or 1; ŵ₁, ŵ₂, ŵ_(i), ŵ_(n-1) and ŵ_(n) represent a firstdecrypted bit value, a second decrypted bit value, an i th decrypted bitvalue, an n−1 th decrypted bit value and an n th decrypted bit value inŴ, the values of ŵ₁, ŵ₂, ŵ_(i), ŵ_(n-1) and ŵ_(n) are 0 or 1;
 2. 3D-HEVCdepth video information hiding method based on single-depth intra modeas recited in claim 1, wherein using w′_(i) to modulate the index of thepixel selected by the coding mode M_(org) ^(k) corresponding to thecurrent CU after being embedded with the hidden information whenencoding the current CU in step (1)_6e and step (1)_6 specificallycomprises steps of marking the index of the pixel selected by the codingmode M_(org) ^(k) corresponding to the current CU when encoding thecurrent CU as I_(org) ^(k) and marking the index of the pixel selectedby the coding mode M_(org) ^(k) corresponding to the current CU afterbeing embedded with the hidden information as Ĩ_(org) ^(k)${\overset{\sim}{I}}_{org}^{k} = \left\{ {\begin{matrix}{I_{org}^{k},} & {{{if}\mspace{14mu} I_{org}^{k}} = w_{i}^{\prime}} \\{w_{i}^{\prime},} & {{{if}\mspace{14mu} I_{org}^{k}} \neq w_{i}^{\prime}}\end{matrix}.} \right.$
 3. 3D-HEVC depth video information hiding methodbased on single-depth intra mode as recited in claim 1, wherein in step(1)_6, a corresponding mode range of a right above neighboring CU of thecurrent CU is a prediction mode set which comprises a 0th predictionmode and prediction modes from a 2nd to a 10th or a prediction mode setgenerated by DMM (Depth Modeling Mode) modes; a corresponding mode rangeof a right neighboring CU of the current CU is a prediction mode setwhich comprises the 0th prediction mode and prediction modes from a 1stto a 25th or a prediction mode set generated by DMM modes; acorresponding mode range of a right below neighboring CU of the currentCU is a prediction mode set which comprises the 0th and the 1stpredication modes and prediction modes from a 11th to the 25th or aprediction mode set generated by DMM modes; a corresponding mode rangeof a left below neighboring CU of the current CU is a prediction modeset which comprises the 0th prediction mode and prediction modes from a26th to a 34th or a prediction mode set generated by DMM modes; acorresponding mode range of a below neighboring CU of the current CU isa prediction mode set which comprises the 0th and 1st predication modesand prediction modes from the 11th to the 34th or a prediction mode setgenerated by DMM modes.
 4. 3D-HEVC depth video information hiding methodbased on single-depth intra mode as recited in claim 1, wherein parsingthe index of the pixel selected by the coding mode M_(dec) ^(k)corresponding to the current CU after being embedded with hiddeninformation and obtaining the i th bit value of the encrypted bit valueŵ′_(i) in step (2)_6e and step (2)_6 is marking the index of the pixelselected by the coding mode M_(dec) ^(k) corresponding to the current CUafter being embedded with hidden information as Ĩ_(dec) ^(k),${\hat{w}}_{i}^{\prime} = \left\{ {\begin{matrix}{0,} & {{{if}\mspace{14mu} {\overset{\sim}{I}}_{dec}^{k}} = 0} \\{1,} & {{{if}\mspace{14mu} {\overset{\sim}{I}}_{dec}^{k}} = 1}\end{matrix}.} \right.$
 5. 3D-HEVC depth video information hiding methodbased on single-depth intra mode as recited in claim 1, wherein in step(2)_6, a corresponding mode range of a right above neighboring CU of thecurrent CU is a prediction mode set which comprises a 0th predictionmode and prediction modes from a 2nd to a 10th or a prediction mode setgenerated by DMM modes; a corresponding mode range of a rightneighboring CU of the current CU is a prediction mode set whichcomprises the 0th prediction mode and prediction modes from a 1st to a25th or a prediction mode set generated by DMM modes; a correspondingmode range of a right below neighboring CU of the current CU is aprediction mode set which comprises the 0th and the 1st predicationmodes and prediction modes from a 11th to the 25th or a prediction modeset generated by DMM modes; a corresponding mode range of a left belowneighboring CU of the current CU is a prediction mode set whichcomprises the 0th prediction mode and prediction modes from a 26th to a34th or a prediction mode set generated by DMM modes; a correspondingmode range of a below neighboring CU of the current CU is a predictionmode set which comprises the 0th and 1st predication modes andprediction modes from the 11th to the 34th or a prediction mode setgenerated by DMM modes.